Mobility management can assist a Long Term Evolution (LTE) communication system in implementing load balancing, providing a better user experience and improving the entire performance of the system.
For convenience of elaboration, a cell serving a terminal currently, namely a cell on which the terminal camps currently, is referred to as a serving cell, and a cell selected or reselected by the terminal is referred to as a target cell. Mobility management functions are mainly divided into two classes: idle mode mobility management and connected mode mobility management, where the idle mode mobility management is mainly self-decided by the terminal on the basis of static parameters configured by a network, and the connected mode mobility management is mainly decided by the network side on the basis of a measurement report of the terminal.
In the idle mode mobility management, the terminal needs to decide, with reference to a minimum receiving level value (expressed as Qrxlevmin) configured by a cell, whether the current cell is a cell suitable to be camped on. In a cell selection stage, if a current signal level value of the terminal is higher than the Qrxlevmin of a certain cell, the terminal will take this cell as a target cell to be camped on. In a cell reselection stage, the terminal firstly sorts measured signal intensity values of neighbor cells which satisfy camp conditions or function values adopting the signal intensity values as variables, then takes a cell with a maximum signal level value or equivalent parameter value of the signal level value as a target cell according to a sorted result, and finally camps on the reselected cell. In this manner, during cell selection, the terminal may make ping-pong reselection between two or more cells due to the fact that the Qrxlevmin of the target cell is higher than a frequency specific Qrxlevmin deployed, in the current cell, for this cell.
In the connected mode mobility management, during selection of a target cell, the target cell is determined only on the basis of a signal level value, reported by the terminal, of a current serving cell, a signal level, measured by the terminal, of a neighbor cell, and resources of the neighbor cell. However, in this manner, a target handover cell selected by the network side cannot totally ensure that the terminal can normally complete random access and other uplink procedures after accessing the cell. Therefore, the effectiveness of cell selection is poor.
To sum up, when cell reselection is made in the current mobility management, the terminal may make ping-pong reselection between two or more cells or the terminal may fail in camping on a cell, or the effectiveness is poor when cell selection is made in handover decision of a current serving cell.